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MARS IS AN unpleasant place.

It’s cold, full of deserts, and has very little oxygen or gravity.

The average annual temperature on Mars around -53°C. At its hottest, Mars could hit 26°C near the equator in the middle of the day. In the Martian winter, however, temperatures could fall to -128°C.

That’s why the first requirement for visiting the red planet would be a spacesuit.

But we were curious: How long could someone survive a summer day on Mars without all this fancy equipment, say, wearing only jeans and T-shirt and while holding his or her breath — which the average human can do for a little more than a minute.

The answers is, unsurprisingly, not very long.

“The most serious immediate impact would be from the low atmospheric pressure that is nearly a vacuum compared to Earth,” Chris Webster from NASA’s Jet Propulsion Laboratory, which manages the Curiosity rover roaming Mars, said in an email.

Within minutes the skin and organs would rupture, outgas, and produce a quick, painful death.

If not killed by the low-pressure atmosphere — there are many other environmental factors that make Mars inhospitable to humans without protection.

“Any humans on Mars would have to contend with the lack of oxygen — only about 0.1 per cent compared to Earth’s 20 per cent — the very cold surface temperatures, the ubiquitous and irritating dust, the intense UV radiation, surface chemicals and oxidants,” Webster said.

And all this before they started looking for food and water!

This post is part of a continuing series that answers all of your “why” questions related to science. Have your own question? Email dspector@businessinsider.com with the subject line “Q&A”; tweet your question to @BI_Science; or post to our Facebook page.

Read: A third of the ‘Mars One’ hopefuls have dropped out … but all three Irish candidates still in the running

Read: So, what are the chances we’ll see an Irishman (or anybody) head to Mars?